Forget the merits of the old and new regimes; there is a sense in which the changing of the political guard is itself a healthy thing. New brooms sweep up fusty thinking, and ministers unembarrassed by past failings speak more plainly about them. William Hague's signal of an inquiry into the UK's embroilment in torture stirs this hopeful line of thought, although optimism must be tempered until the detail has been published, and certified devil-free.

The new foreign secretary is not always a friend of human rights, but those who are should welcome his promise of an early judge-led investigation into torture allegations. Potentially this represents a great advance on his predecessor, David Miliband, who restricted himself to talking about prospective proceedings against individual agents. That one-rogue-at-a-time response was inadequate because the allegations which have steadily emerged over five years – not least in the pages of the Guardian – raised questions about whether the whole culture of Britain's security state was rotten.

Recall that the torture of the UK resident Binyam Mohamed has been established and that many others seem to have been mistreated in Pakistan. Recall, too, that after 9/11 British agents operated under a policy which freed them of the need to discourage their foreign counterparts from using torture, a policy Tony Blair knew about. The only way to get to the bottom of all this is an open judicial inquiry, with a sweeping remit and unlimited access to papers. Mr Hague fell short of promising this when pressed. It is worrying that the coalition agreement says nothing more specific than that "we will never condone torture", a statement the Blair administration could cheerfully have made, even in its most frenzied days.

A fresh government provides a chance for a fresh start, including in foreign relations. Washington might prefer to keep things quiet, but should be told that UK ministers have no more power to keep shaming secrets under wraps than their US counterparts. After all, increasingly assertive courts have being deciding which security papers come to light, and judges have been saying some remarkable things about MI5's trustworthiness. Only yesterday the coroner investigating the deaths on 7/7 ruled that the service must face her spotlight. The cry of national security no longer closes down discussion as it once did, and even secretive power must be accountable.

The coalition should respect these trends and launch an unfettered inquiry, headed by a vigorous judge. To adapt Barack Obama, our security will in the end be better advanced by the power of our example than by our acquiescence in brutish power.